The present invention relates to a refiner for processing fiber material, consisting of two oppositely arranged grinding discs which are driven by an electric motor and of which the end faces facing each other comprise processing devices with material grinding barriers and cutters, respectively, which are arranged in groups along the circumference of the grinding discs in sectors extending parallel to each other and interposed flow canals.
Such refiners are known, for instance, from DE-OS No. 25 22 349 (U.S. Pat. No. 3,910,511), U.S. Pat.No. 4,351,489 and DE-OS No. 27 24 161. The refiners serve for comminuting raw material, for instance, wood chips, by means of rotating processing devices which are arranged on the oppositely disposed end faces of grinding discs. These grinding discs are driven by electric motors in that either only one grinding disc rotates and is set against a stationary disc, or two grinding discs rotating in opposite directions of rotation are moved against each other, and are driven by a separate electric motor each. The material to be comminuted is fed to the space between the two grinding discs, runs through them generally radially from the inside out and leaves the refiner as a paste.
The processing devices of the known grinding discs with the mutually parallel extending material grinding barrier or cutter groups and flow canals located in between are arranged interchangeably on sectors of the grinding disc. These sectors all have the same size. The cutters supported by them have a uniform arrangement in the groups; they generally make an angle with the radius. The geometric arrangement of the processing devices depends on the raw material to be processed. A subdivision of the sectors into two or more radially successive ring sectors with a different arrangement of the material grinding barriers or cutters is known.
Depending on the output of the refiner, the latter and the driving electric motor are equipped with bearings of their own and, in the case of large ratings, are connected to each other via flexible but rotation-rigid couplers. In the case of smaller ratings, the grinding discs of the refiner and the rotor of the driving motor are arranged on a common shaft. The operation of the refiner subjects the driving electric motor to heavy stresses which can have vibration problems as a consequence and resulting therefrom, also damage. It is therefore customary to overdesign the parts of the refiner and in particular, also the mounting parts of the rotors of the drive motors, in order to prevent damage.